Thursday, June 10, 2010

Nitrate: a Protective Factor in Leafy Greens

Cancer Link and Food Sources

Nitrate (NO3) and nitrite (NO2) are molecules that have received a lot of bad press over the years. They are thought to promote digestive cancers, in part due to their ability to form carcinogens when used as a preservative for processed meat. Because of this (1), they were viewed with suspicion and a number of countries imposed strict limits on their use as a food additive.

But what if I told you that by far the greatest source of nitrate in the modern diet isn't processed meat-- but vegetables, particularly leafy greens (2)? And that the evidence linking exposure to nitrate itself has largely failed to materialize? For example, one study found no difference in the incidence of gastric cancer between nitrate fertilizer plant workers and the general population (3). Most other studies in animals and humans have not supported the hypothesis that nitrate itself is carcinogenic (4, 5, 6), but rather that they are only carcinogenic in the context of processed meats due to the formation of carcinogenic nitrosamines. This, combined with recent findings on nitrate biology, has changed the way we think about this molecule in recent years.

A New Example of Human Symbiosis

In 2003, Dr. K. Cosby and colleagues showed that nitrite (NO2; not the same as nitrate) dilates blood vessels in humans when infused into the blood (7). Investigators subsequently uncovered an amazing new example of human-bacteria symbiosis: dietary nitrate (NO3) is absorbed from the gut into the bloodstream and picked up by the salivary glands. It's then secreted into saliva, where oral bacteria use it as an energy source, converting it to nitrite (NO2). After swallowing, the nitrite is reabsorbed into the bloodstream (8). Humans and oral bacteria may have co-evolved to take advantage of this process. Antibacterial mouthwash prevents it.

Nitrate Protects the Cardiovascular System

In 2008, Dr. Andrew J. Webb and colleagues showed that nitrate in the form of 1/2 liter of beet juice (equivalent in volume to about 1.5 soda cans) substantially lowers blood pressure in healthy volunteers for over 24 hours. It also preserved blood vessel performance after brief oxygen deprivation, and reduced the tendency of the blood to clot (9). These are all changes that one would expect to protect against cardiovascular disease. Another group showed that in monkeys, the ability of nitrite to lower blood pressure did not diminish after two weeks, showing that the animals did not develop a tolerance to it on this timescale (10).

Subsequent studies showed that dietary nitrite reduces blood vessel dysfunction and inflammation (CRP) in cholesterol-fed mice (11). Low doses of nitrite also dramatically reduce tissue death in the hearts of mice exposed to conditions mimicking a heart attack, as well as protecting other tissues against oxygen deprivation damage (12). The doses used in this study were the equivalent of a human eating a large serving (100 g; roughly 1/4 lb) of lettuce or spinach.

Mechanism

Nitrite is thought to protect the cardiovascular system by serving as a precursor for nitric oxide (NO), one of the most potent anti-inflammatory and blood vessel-dilating compounds in the body (13). A decrease in blood vessel nitric oxide is probably one of the mechanisms of diet-induced atherosclerosis and increased clotting tendency, and it is likely an early consequence of eating a poor diet (14).

The Long View

Leafy greens were one of the "protective foods" emphasized by the nutrition giant Sir Edward Mellanby (15), along with eggs and high-quality full-fat dairy. There are many reasons to believe greens are an excellent contribution to the human diet, and what researchers have recently learned about nitrate biology certainly reinforces that notion. Leafy greens may be particularly useful for the prevention and reversal of cardiovascular disease, but are likely to have positive effects on other organ systems both in health and disease. It's ironic that a molecule suspected to be the harmful factor in processed meats is turning out to be one of the major protective factors in vegetables.

59 comments:

awesome post.. i was just chatting with a co worker about this today... she is a vegetarian, and was telling me while i was eating a sandwich made with deli meat how awful the nitrates were for me. I told her that if nitrates were bad for us, we should all stop eating vegetables, because they are full of them!!

Thanks for posting this. I found this out for myself while researching nitrates for my website. When anyone gives me the "processed meats will kill you" line, I point out that celery juice is used as a curative for "naturally" processed meats because it has way more nitrate in it than any store bought hotdog. :)

Do you think the method of processing has anything to do with the carcinogenicity of processed meats? I wonder if meats that are processed with artisanal methods would have the same negative effects as commercially processed meats?

I don't know much about mouthwash, but it seems like a bad idea to try to kill all the bacteria in one's mouth. Particularly in light of the fact that they seem to be helping us out in some ways.

Hi Chris,

I don't know. I'd like to see the level of AGEs in commercially and traditionally processed meats. It may be relevant that many traditionally preserved meats are not cooked. On principle, I think fresh meat is likely to be generally healthier than processed meat of any kind.

Nice article, but how about proteins as the NO source? I seem to recall that even small dietary protein excess (i.e. protein used for fuel, not for building) was deemed to be a great way to produce NO?

Furthermore, some extra protein helps in choosing the best and most needed ones for building, while utilising the rest for both fuel and antioxidant production...

On this article from hyperlipid:http://high-fat-nutrition.blogspot.com/2008/06/ihd-and-ghee.html

In the comments there is a discussion as to whether dietary AGEs matter or not.

One commenter points out:"There may be more AGEs in cooked meat but the meat also contains carnosine, which prevents absorption of AGEs. Vegetarians have far higher AGE serum levels despite generally using gentler cooking methods because they consume a great deal of fructose. Fructose is 7-10 times more reactive than glucose."

Do you have a link to the animal studies? I am skeptical about the epidemiological studies because that would be based on crappy hot-dogs with any number of additives in an enriched white flour bun.

Stephen-I find it interesting that many of your posts run contrary to the philosophies of many of the blogs that link to you. Your not so anti-grain and carbohydrate posts as well as your greens are good for you posts (some in the paleo community claim that there is little evidence that plant foods are a healthy part of the human diet-usually backed up by pointing out their chemical defense systems). I suppose they respect that your posts are not emotionally charged and research based (as do I).

I have wondered about this. Especially in the context of high stomach cancer rates among Koreans (highest in the world), which some have attributed to the very high nitrate levels in kimchi (made from Napa cabbage). Care to offer a hypothesis on the possible reason for this? Their diets are also very heavy on salty and fermented foods.

I refuse to believe that I need to consume these tasteless and bitter green leaves to be healthy. Im tired of having the anecdote of "if you dont eat vegtables you cant be healthy" mantra shoved down my throat.

Like other people have said, plants dont want you to eat thier leaves, they are full of toxins and poisons thats why they taste bitter!

Great post. I tend to follow a more hyperlipid diet and am in excellent health, but the garden is producing such wonder leafy greens and tomatoes that I'm eating tons of salads. I believe it's having a small calming effect on me. I remarked on this to a friend before I read this post. Perhaps it has something to do with nitrate.

wouldnt it be safe to say, evolutionarily, we did not eat many green veggies, ie low carb veggies AT ALL and focused on tubers/root and meat/organs... i just cant be convinced theres any room for collecting lettuce and celery when there is rutabagas and butternut squash... any comment?

If you read the post again, you'll see that I did not confuse nitrate and nitrite. Since nitrate is converted to nitrite, results that apply to nitrite also apply to nitrate. That's the assumption I was operating under, and it's one that's well supported by the literature I cited in the post.

I wouldn't dismiss the possibility that green leafy vegetables are potential causes of gastric cancer so quickly. I'm aware of at least 3 or 4 studies that have found than vegetables are associated with greater incidence of cancers of the upper GI tract (surprising since most confounding would be expected to go the other way. Here's one example: http://www.wjgnet.com/1007-9327/11/3834.asp

Here's another very interesting ph.d. thesis with studies attached: http://theses.gla.ac.uk/394/01/2008patersonphd.pdf

I think you make an important point. I've thought about that as well. Modern nutrition experts seem to operate under the assumption that in the rosy past, our ancestors ate a ton of vegetables. But I'm not convinced that's true, since vegetables are low-yield from a calorie standpoint and don't keep well.

That being said, there is plenty of evidence that certain hunter-gatherers and non-industrial agriculturalists sought out greens and other vegetables because they enjoyed eating them. I'm not clear on how common it was, or how much they ate, but I would love to know. It's often thrown around that equatorial HGs ate a lot of vegetables, but I've never seen any convincing evidence to support those vague statements. I do think it's worth noting that some root vegetables such as beets, carrots and turnips contain a lot of nitrate. Potatoes and sweet potatoes don't contain much.

@Brian: I'd be inclined to blame all the chili peppers in kimchi for the high stomach cancer incidence, though opinion seems to be divided as to whether capsaicin in peppers is actually carcinogenic or anticarcinogenic.

Here's another idea on whether we would have eaten greens while evolving. It seems that most people like to eat greens, at least in small amounts. Personally I find the idea of never eating green vegetables to be pretty depressing. Even Kurt Harris, who thinks veggies are completely overrated admits that he enjoys greens as a side dish or condiment. With this in mind, the question arises - why would we have evolved to like eating greens? Unlike sugar or other stuff that we like and isn't good for us, greens do no have a huge caloric bonus. So, what other reason would we have developed a taste for them? There must be something of value in them.

I am always a bit suspicious of processed meats such as the likes of sausages that often contain sources of gluten which may have a link with gastric cancer. And the consumption of these processed meats may be a marker for consumption of other foods that promote gastric cancer. At this stage, the evidence just isn't strong enough to get me to give up my free-range gluten free streaky bacon!

Informative post and comments. I have a question for Stephen or anyone that knows about this. How does nitrate get into the processed meat in the first place? Is it in a whole food from or is it isolated? And is this preservative isolated from a natural source or is it chemically produced? Thanks and hope to hear back from you all!!

We had a higher rate of stomach cancer a couple generations ago when all of our foods were pickled and salted too. Modern refrigeration probably allowed those GI cancers to go down, around the same time our lung cancer rate shot up (from the introduction of cigarettes).

Koreans have kept the highly salted fermented food in their diet, and they eat these 'banchan' at every single meal as a significant portion. Most banchan also contain red pepper, like someone else noted. If all the salt and red pepper was not enough in the 5 side dishes you're served, your "jiggae" (soup) is probably extremely salty and filled with red pepper, so much so that it tastes bad unless you even it out with rice.

Very interesting post. So the problem with processed meat really isn't the nitrates.

I expect you're right about AGEs. But there might be another factor too: processed meat is often eaten together with white bread. The meat-and-white-bread combination has the potential to cause iron-manganese imbalance, which means oxidative stress.

As I like to track down new sports supplements, this stroke me hard. A short study, sure. But the gain in oxygen cost was insane:

“The principal original finding of this investigation is that three days of dietary supplementation with nitrate-rich beetroot juice (which doubled the plasma nitrite) significantly reduced the O2 cost of cycling at a fixed sub-maximal work rate and increased the time to task failure during severe exercise,” wrote Jones and his co-workers.

“That an acute nutritional intervention (ie, dietary supplementation with a natural food product that is rich in nitrate) can reduce the O2 cost of a given increment in work rate by about 20 per cent is therefore remarkable,” they added.

Mechanism

"It is unclear what the exact mechanism behind the apparent benefits is, said the researchers. They do, however, suspect it could be a result of the nitrate turning into nitric oxide in the body, reducing the oxygen cost of exercise."

Sorry, some (original) repasting above - the main point for skimmers is that beetroot is a good nitrate source -> more NO and vasodilation -> more oxygen to tissues.

Carnosine in meat seems to do the same, as well as being a great anti-AGE-product dipeptide and H+ blocker. It's precursor beta-alanine, which rises carnosine concentration more effectively in the muscle tissue, is one of the most researched sports supplements in the recent years.

So I wonder if there is some considerable overlap with these substances if ingested concurrently ?

Hi Stephan,Could you answer Woly's question regarding nitrosamines?I think it is interesting to consider the difference between potassium nitrate and sodium nitrate and generally the higher level of salt in the processed meats as having an influence over the balance between Na and K in the human body. (from Wiki)"In the process of food preservation, potassium nitrate has been a common ingredient of salted meat since the Middle Ages,[5] but its use has been mostly discontinued due to inconsistent results (regarding the growth of bacteria) compared to more modern nitrate and nitrite compounds."

In 2007 I went to two lectures at the MRC Human Nutrition Research here in Cambridge.The first was by Prof. Sheila Bingham. a principal investigator on the EPIC study. In that study they found no correlation between fruit and vegetable intake and mortality, however there was a "very significant" correlation between blood ascorbate (vit C) levels and mortality and the bar graph she displayed to us showed steeply declining mortality between ascorbate levels corresponding to less than one 50g portion of plant food per day and five portions where it levelled out.The study found the level of bowel cancer was about 1.3 times higher in red-meat eaters as in non red-meat eaters.They investigated the damage to DNA in the enterocytes (that are shed continuously from the gut and can be extracted from the faeces) with various protein sources. The DNA damage from vegetable protein was low, that from fish and white meat slightly higher but red-meat caused many times as much DNA damage.So why is bowel cancer only 1.3 times higher in red-meat eaters? They looked at common foods that might protect against cancer. They found that when dietary fibre, particularly Resistant Starch, was eaten with the red-meat the DNA damage was considerably reduced but still above the level for vegetable protein.The next lecture was by one of her colleages from the Dunn Human Nutrition Unit and he did the same thing with chlorophyll. He found that eating the amount of chlorophyll found in one tablespoon of spinach with the red-meat reduced the DNA damage slightly below the level for vegetable protein.In the wild all mammal carnivores eat the stomach of their prey first (not always all of the contents but some vegetable matter). Plains Indians were famed for eating the raw intestines of the buffalo along with its contents (mostly finely chewed grass) and the Sami of Lappland still get their vegetables this way. The Maasai, Samburu and other pastoralists who "disdain vegetables" usually eat more variety of plant foods than many vegetarians, much smaller quantity but carefully chosen see:http://donmatesz.blogspot.com/2010/01/masai-use-of-herbs.htmlMembers of the cat family have evolved for millions of years eating and drinking the ascorbate rich parts of their freshly killed prey yet they still make their own Vitamin C. You cannot get an optimal intake of ascorbate from an all meat diet, although you can avoid scurvy.The EPIC study found no reduction in mortality from taking vitamin C supplements but the people who chose to take them were probably getting enough already.For people who don't like greens, wheat-grass and barley grass juices are a good substitute and widely consumed in Japan.Jay

Interesting, I didn't realize saltpeter is K nitrate and not Na nitrate. What woly said is a leading hypothesis of why there's an association between processed meat and gastric cancer. I think it's plausible.

Stephan,I forgot to mention that pastoralists generally are averse to browned meat, in Tibet it is taboo to heat meat above boiling point and the Iranian herdsman in a TV documentary after tasting a medium steak offered by the camera crew said in subtitles "I'm sorry I can't eat this it's burnt"

Greg,I have seen plenty of references to eating the stomach and gut contents of their food animals, these are usually green.

That link you posted about the Maasai eating carefully chosen herbs is very interesting. It seems at least one of the herbs is high in tannins, which would bind iron and prevent its absorption. I've wondered for years how the Maasai avoid iron overload.

'In the wild all mammal carnivores eat the stomach of their prey first.'

I've heard this too, but it seems it isn't true. People who observe carnivores in the wild say the stomach contents are the only part NOT eaten. Have a look at this:http://www.rawfed.com/myths/stomachcontents.html

Red meat may indeed be associated with cancer due to cooking temperatures, but I wonder if it also has to do with an excess of heme iron.

I haven't looked into this, but I recently read about a strong correlation between heme iron intake (heme iron is the kind from meat) and insulin resistance, and, by extension, Type II diabetes. It could be that the correlations some studies have found between red meat intake and poor health have more to do with heme iron than the probable non-issue of saturated fat.

I also wonder what else is in the modern meat. Hadn't considered the difference between potassium nitrate and sodium nitrite as an additive.

Some processed meats are injected with "mix", a solution of water containing various salts to bulk it up with retained water, and protein from other species which has been denatured to prevent its identification via DNA. You wouldn't find this crap in Real Meat.

Anecdotally, one of my cats likes watermelon, tomatoes, peas, and corn (unbuttered, on the cob). He turned up his nose at a plate of lamb I'd cooked up when he was on a hypoallergenic diet.

The observation some have made about animals eating organ meats (not the stomach) first has been used as proof that these are the most nutritionally valuable parts of the animal. I don't doubt it, but they are also the most perishable, so that may factor in as well.

JaneIn fact iron overload is quite common among the Maasai but as they visit the tribal herbalist about once a fortnight they adjust their herbs and it rarely becomes serious.In the Stefansson and Anderson "all meat" diet they were allowed black tea and coffee, plenty of tannins there to prevent iron overload.I have read that the most common cause of anemia in the UK is drinking tea with meals and not a low iron diet.I had read the rawfed article before, it certainly doesn't contradict what I said. Wolves are pack animals and hunt animals many times larger than themselves, the gut contents of a prey animal can be many kilos, of course they only eat a tiny proportion of this.I have seen a domestic cat kill and eat a mouse on two occasions and both times it ate the entire stomach contents.On numerous occasions I have seen dogs and cats eat grass and Cindy Engel in her book mentions many other examples.I guess that over 0.5% of a wild carnivore's diet (by weight not calories) is normally vegetable matter and much more during the autumn if they eat fruit (in the UK foxes like pears).

HelenI agree that heme iron is important and have read that the production of N-nitroso compounds is greatly increased in the presence of heme iron whether from red meat or supplements.

Stephan - your blog is the best, and I am in the process of reading it all. I think you should point out that nitrosamines are proven carcinogens in animals. This was discovered when animal feed with high levels of nitrosamines (formed from fish and sodium nitrate) caused large numbers of cattle to die of cancer. Apparently vitamin C will block nitrosamine formation in cooking, and break it down endogenously (Mark Sisson had a good post on the MDA blog explaining this). I think people need to keep in mind that despite what the FDA claims, tests of meat preserved with sodium nitrate prepared according to instructions, does still contain nitrosamines - up to 10x the "safe" limit. Nitrosamines concentrate in the fat. I would suspect that further frying with the rendered bacon fat could cause the formation of more nitrosamines.There is an interesting paper regarding the decrease in stomach cancer correlating with the decrease in the use of nitrates.My take-away is to make sure not to cook any nitrate (or celery salt) preserved meat at high temperatures (<230 F), do not use the rendered fat, and use in moderation along with fruits and veggies that are a source of vitamin C - BLT anyone?Except pregnant women- cured or processed meats have been linked with birth defects.

There were a couple of comments on mouthwash and its role. Yes there is evidence that using mouthwash causes dramatic plunge in saliva's nitrite levels after oral nitrate load. So using regular mouthwash might offset cardiovascular benefits.

It would be interesting to know if the nitrates naturally present in green vegetables behave, after ingestion, in the same way as those added to meat products as preservatives. Does vitamin C in vegetables neutralise the ni-trosamines that might be created in the stomach in reaction with the gastric acid. Anyway, I think, it would be foolhardy to suppose that adding E250 (Sodium nitrite) to sausages increases their nutritive value, or that it has positive health effects in any way.

the following post on nitrates and nitrites, which I am hoping you can address:

On April 7, 2011, a former surgeon general and Dr. Suzanne de la Monte appeared on the Dr. Oz Show entitled, "A Revolutionary Breakthrough in Alzheimer's Disease," (can be watched on his website) where she presented her important research. She is the doctor who coined the term "type 3 diabetes" in reference to Alzheimer's disease.She found by accident that giving a nitrosamine compound called streptozotocin, used to deliberately produce diabetes, caused Alzheimer's in her lab mice.

She learned that the brain produces its own insulin. She further found that this compound causes production of toxic lipids in the liver that cross the blood brain barrier and damage certain cells such that the brain develops insulin deficiency and insulin resistance. Nitrites and nitrates, found in very many processed foods, are nitrosamine compounds and could very well explain the epidemics of Alzheimer's, autism, diabetes, MS, Parkinson's and ALS, along with other neurodegenerative diseases that have insulin resistance, decreased glucose uptake as part of the process. These diseases have all been on the increase as processed foods have taken over our diets.

I will add Dr. de la Monte's references to the website http://www.coconutketones.com/, in the very near future. These nitrites and nitrates are in most bacon, ham and other meats, deli meats, whether pre-packaged or cut at the counter, processed cheeses, cereals, breads, pretzels, crackers, white flour and anything that contains white flour, certain beers, scotch and some other whiskeys.

Now something that has caught my attention for newborns and children: I found one of these offending compounds, thiamine mononitrate, in the Carnation infant formulas, some of the jarred baby foods, especially the junior combinations, cereals and other infant prepared foods such as macaroni and cheese. The government requires that certain vitamins such as thiamine are added to enrich foods that have been stripped of these nutrients by processing, most notably white flour and other grains.

Thiamine mononitrate is a synthetic source of vitamin B1, rather than a naturally occurring vitamin, and is added to very many foods. Just look at the ingredients labels. Most people eat something with thiamine mononitrate in it for nearly every meal. Naturally occurring Vitamin B1 (thiamine) is usually water soluble, meaning that if you eat an excess of it, you will pass it out in the urine; however, thiamine mononitrate is fat soluble and the excess accumulates in the liver and fat cells.

The FDA regulations (21 CFR 184.1878) say that thiamine mononitrate may be used in food "with no limitation other than good manufacturing practice" and that it "may be used in infant formula". These compounds could slowly kill off insulin producing cells in the brain and other organs, and when enough cells have been effected symptoms will begin to emerge.

This could explain the classic development of autism in children at 1 1/2 to 2 years of age who were previously thought to be normal. And in Alzheimers' it is believed that the disease process begins at least 10-20 years before symptoms appear. Animal studies need to be done to determine if thiamine mononitrate produces Alzheimer's disease, autism, type 2 diabetes and the other diseases mentioned above.

In the meantime, it would behoove us to read the labels and eliminate anything from the diet that includes nitrosamines, nitrites, nitrates; look for these words alone or in combination with other words, such as thiamine mononitrate. What is left for us to eat? Stay away from packaged and other processed foods and eat whole foods: organic whenever possible, vegetables, fruits, eggs, dairy, goat milk and cheeses, nuts, legumes, whole grains (without added nitrates) grass fed beef, free range chicken, "natural" deli meats that have nothing added (they can be frozen to prolong use).

I thought we were adhering very closely to a whole food diet until learning that many of the foods we were eating, such as deli meats and some "whole grain" breads and cereals, contain nitrites or nitrates. this could explain some of the deterioration we have seen in spite of everything else we are doing. Most important to our newest generation, mothers can avoid this problem by breastfeeding their babies for as long as possible. Nitrites and nitrates are just one group of compounds we need to worry about for our newborns and toddlers. Also, consuming foods with medium chain fatty acids, such as coconut oil and MCT oil, can at least partly bypass the problem of insulin resistance by providing an alternative fuel to glucose for brain cells.

And how could this possibly be related to the herpes simplex issue that I have written about? I found a 1977 article from the lab of Dr. George Cahill, Jr. ("Studies of Streptozotocin-induced insulitis and diabetes", Proc Natl Acad Sci USA, 74(6): 2485-2489, June 1977), in which he used streptozotocin to produce diabetes in mice by destroying the beta cells of the pancreas-- an unexpected finding was an increased production of a type C virus in the beta cells that survived.

Could it be that the virus is involved as part of the process that destroys the cell after exposure to nitrosamines, or is an opportunistic infection that takes over the damaged cells, which further complicates the Alzheimer’s disease process? The bottom line is to avoid any foods that contain nitrites or nitrates or any ingredient in which one of the words appears.

Woly said: " Nitrates change into nitrosamines under high temperatures (frying) and when mixed with amines (protein). This process also seems to be disrupted by vitamin C. Could it be that because vegetables are low in protein, rich in vitamin C and are generally not fried at high temperatures, they escape the carcinogenic potential while bacon results in the opposite?"

The issue that Woly is raising is what should be studied carefully. Various people on the web are intentionally trying to make it sound as if smoked, nitrite-cured, processed meats such as bacon and lunch meats have the health advantages of vegetables without considering what undesirable compounds may form during cooking and in the digestive tract. Bacon is of particular concern since it is often fried at high temperature (fried bacon also has very high AGE content). Studies to date in general have shown health risks of such processed meats while numerous studies have shown health advantages of fresh vegetables.

In the U.S. market, ascorbic acid is added to nitrite-cured meats in an attempt to thwart the formation of nitrosamines. The addition of ascorbic acid doesn't necessarily guarantee inhibition of nitrosamine. Ascorbic acid in the presence of fat and the acidic environment of the stomach can potentially promote N-nitrosation. In vivo studies are needed. See the paper below. It's online for free.

I'm trying to find out whether the nitrates in vegetables are different depending on whether they are from a man-made fertilizer or whether they are from a "natural" source. I actually got here from looking at info on nitrates in animal forage being toxic at certain levels. The agricultural info I've found says drought can cause nitrate accumulation in forage to toxic levels (for the animal) and this can happen a couple weeks after fertilization with either synthetic fertilizers (whether nitrate or urea) or manure application. But I am just wondering if some of the nitrogen in the manure would be from synthetic fertilizer anyway.

But the basic question is whether all forms of nitrates in plants have same effects in human nutrition or whether the type of fertilizer used in the plants makes no difference.

As a gardener I have noticed that not all fertilizers are labeled for use on edibles, and I think that has to do with the form of nitrogen (but I'm not sure). I have a hydroponic unit that came with fertilizer of a special kind which is supposed to be okay for growing vegetables, and I have watercress growing. Fertilizer says "1.0% Ammoniacal Nitrogen, 3.0% Nitrate Nitrogen". So is my watercress going to contribute more to health or to brain degeneration?

I probably don't have enough chemistry background to really understand any responses but I will be working on it because although my family and I eat less processed food than average, we eat what we grow and I also feed animals and my family, and would like to make informed choices about eating cultivated greens and what fertilizer choices are safest.

About Me

I'm a writer and science consultant with a background in neuroscience and obesity research. I have a BS in biochemistry and a PhD in neurobiology. I'm the author of "The Hungry Brain: Outsmarting the Instincts That Make Us Overeat".

Copyright 2008-2017

Please feel free to reproduce the contents of this blog, on the condition that you:

1) Attribute the work to me

2) Provide a link to the page where you found it

3) Do not use it for commercial purposes

Financial disclosure

I am a co-creator of the Ideal Weight Program, and I receive revenue from the sale of this program.

In addition, I am registered as an Amazon affiliate. I may receive a small commission on the sale of some of the books I review, or other products sold through Amazon.

Disclaimer

This blog is a compilation of my opinions. It's not advice; it's information that you can take or leave as you please. I don't intend it to replace professional medical consultation or treatment. Your health is in your own hands.